None.
Not Applicable.
1. Field of the Invention
This invention relates generally to devices intended to receive the human body in a prone, supine, or sitting position and, more particularly, a composite mattress having an improved sleep surface and edge support.
Current conventional mattresses are known which are composed primarily of foam material. These foam mattresses are useful, but they could be improved. The foam material used for mattresses comes in high resilience and low resilience types. Unfortunately, high resilience foams, such as latex or viscoelastic foams, are relatively expensive as compared to less resilient foams such as polyurethane foams.
Consumers and retailers desire a high profile mattress which can be anywhere from twelve to twenty five inches in height. Current manufacturing technology for the high resilience latex foam can produce a sheet up to six inches in thickness. Mattresses made entirely from the more desirable high resilience foams can easily become too expensive for general use. The low resilience foams can be manufactured in thicknesses of four feet or more. A conventional foam mattresses made entirely from low resilience foam must be rotated and flipped frequently (every few months). Composite mattress have been developed which use both types of foams.
2. Related Art
U.S. Pat. No. 82,975 to Morey discloses what appears to be one of the first patents covering a mattress. The invention saw an excelsior such as moss, hay or straw sandwiched between layers of sponge. Fortunately, technology in this area has continued to develop.
U.S. Pat. No. 2,831,532 to Kasper discloses laminating layers of fiberglass, foam rubber, cotton matting or sponge rubber to create cushions or mattresses. This is one of the first uses of layering for support and comfort. U.S. Pat. Nos.: 6,223,371; 6,295,674; 6,159,574; 5,745,940; and 3,939,508 all teach using different types of foam in varying configurations.
Customers complained that some early foam mattresses xe2x80x9cbottom outxe2x80x9d. This occurs while the occupant sits on the edge of the bed. The mattress can support the weight of the occupant when lying on the bed, but the concentration of the weight in one spot as when sitting causes the bed to dip or buckle in that spot. U.S. Pat. No. 5,701,623 to May shows a composite mattress which uses firmer border sections to provide additional support when a person sits on the edge of the mattress. My own U.S. Pat. Nos.: 6,256,821 and 5,960,496 (herein incorporated by reference) disclose a mattress system with a firm core 21. Although not stated specifically in the patents the core 21 provides support on the side to prevent bottoming out.
One of the problems created by the use of a firmer material on the side of the mattress is the transition from the sleep surface to the edge of the bed is noticeable and affects the quality of sleep. There does not currently exist a mattress which provides the benefits of the foam sleep surface and the support of the firmer border sections that has a consistent sleep surface.
Accordingly, there is a need for a high profile, low maintenance mattress which can be made economically by combining both high resilience foam and low resilience foam. The low resilience foam can be used in the base to provide support, and the high resilience foam can be used to provide a comfortable sleep surface. The challenge is to provide a mattress with edge support sufficient to avoid xe2x80x9cbottoming outxe2x80x9d and a smooth transition to the sleep surface.
It is in view of the above problems that the present invention was developed. The invention is a composite foam mattress having a base made of a firm foam and a sleep surface of a softer and more dense foam. In the first embodiment the base is configured with a channel and the sleep surface rests in the channel. The channel is created by a pair of edge supports. In the second embodiment the edge supports are located on all four sides of the mattress creating a well. These edge supports prevent the mattress from buckling when a person sits on the edge of the mattress. In the third embodiment, the mattress has a base surrounded by edge supports such that the base and the edge supports are the same thickness. The sleep surface covers both the base and the edge supports. The sleep surface is made of a higher density foam and is shaped such that the edge supports are covered at a predetermined thickness. With as little as two inches of foam material a smooth, unnoticeable transition is created. A consumer will feel support when sitting on the edge of the mattress, yet not feel the harder base material when prone and the body weight is dispersed.